The invention relates to an operating mechanism for a four-pole electrical breaking apparatus, notably a circuit breaker comprising three poles respectively associated with the three phases and one pole associated with the neutral.
Generally speaking, the mechanism controlling opening and closing of a circuit breaker is associated with one of the poles. For three-pole circuit breakers, this mechanism being associated with the center pole, the lateral forces are distributed symmetrically on each side of the mechanism. For four-pole circuit breakers, the asymmetry introduced by the position of the mechanism gives rise to problems of flexion and/or torsion on the coupling means connecting the poles to one another. The document U.S. Pat. No. 4,383,146 proposes a solution to the above-mentioned drawbacks, which consists of adding an auxiliary mechanism to the pole associated with the neutral. This auxiliary mechanism modulates the resistive torque in the course of the operation due to an angular offset between the three poles associated with the phases and the pole associated with the neutral which defers actuation of the neutral pole; this mechanism notably comprises a compression spring to compensate the friction forces and favor passage of the dead point.
On account of its design, the above-mentioned solution does not enable the opening and closing operations of the four poles to be performed perfectly simultaneously. Moreover, it does not enable manufacture of the poles to be rationalized due to the differences existing between the poles associated with the phases and the pole associated with the neutral. Finally, the mechanism is subjected to large fatigue phenomena.
The object of the invention is to overcome the above-mentioned drawbacks and to enable a simple, economical, rugged and reliable four-pole circuit breaker to be manufactured.